Improved annealing-pit for annealing car-wheels



w. 1. COCHRAN.

i Annealing Car Whels.

No. 83,605. l l- Patented Nov. 3, 1868.

Y l C d MM Qf/MW/ v UNITED ISTATES PATENT OFFICE.

WILLIAM' J. COCHRAN, OF BALTIMORE, MARYLAND, AssIGNOR 'ro HIMsELr AND JOHN OOOHRANE, OF FARMINGDALE, NEW JERSEY.

IMPRO'VED ANNEALING-PIT FOR ANNEALING CAR-WHEELS.

Specication forming part of Letters Patent No. 83,605, dated November 3. 1868.

To all whom it may concern.'

Be it known that I, WILLIAM J. COCHRAN, of the city and county of Baltimore, and State of Maryland, have invented certain new and useful Improvements in the Pits or Chambers for Cooling or. Annealin g Railroad-Car-Wbeely Castings,by means of which improvements unequal shrinkage in such castings is completely prevented; and I do hereby declare that the following is a full and exact description there of, reference being had to the accompanying drawiugs,and'to the tigures and letters marked thereon, and in which- Fi gurel. isa vertical section through the axis of the cooling-pit, and Fig. 2 atop view of the same.

In both figures the same part'sare indicated by the same letters. j

The deterioration in the strength of iron castings from unequal cooling and shrinkagethat is, from the cooling of the thin parts of the casting previous to the cooling ot' thethick parts of itl-arises from the peculiar strains that are thrown upon the different parts of the casting by such unequal cooling. Those parts that cool first endeavor by their contraction to pull from or sever their connection with the hotter portions, thus producing not only incipient tracture at or near the line of junction ot' such thin and'thick parts, but au enlargement also ofthe thinner pprtions of the casting by the consequent dragging'out ofthel particles.

1n railroad-wheels the central plate or disk, being the thinnest part of the casting, is the first to cool, and in so doing it `pulls from the rim, causing a. partial separations; dragging out of the particles ot' the iron or stretching of the substance, thereby making an incipient fracture at or near the line of junction within the rim, and in like manner'the cooling ofthe hub causes it to pull from the central plate, thus making an incipient fracture at the line `ofjunction around the hub. These strains give a permanent enlargement to the central plate of the wheel by the dragging out or partial separation of4 the particles of the ir'on, which enlargement of the central portion of the wheel in the next place resists 4the proper contraction of the rim which surrounds it, audthereby I causes a number ot' incipient radial fractures to be formed init or to be greatly and injurionsly strained by its shrinkage on the central plate. t The vetect; of these strains upon the wheel is to cause the rim, and also the junction between the hub and theentral plate, to become very brittle fromthe disturbance ordislocation of the particlesby the stretching of the metal, and therefore very liable to fracture; and it sometimes happensthat such wheels will burst from these causes alone before. leaving the foundry in which they were cast. these well-known evils a great variety of forms have been devised, so as to give that portion of the wheel which is between the rim and the hub some flexibility; in order that it might thereby compensa te for the unequal cooling or contraction of the several parts, and in`this manner a small advantage has been realized, inasmuch as some of these wheels will ontlast others of more rigid construction that were cast from the same mixture of metal; but upon experimentally testing the ability to resist frac ture in the best of such wheels it is found that they all come far short of the degree of strength which is due to the quantity and quality ot the iron of which they were respectively1 composed. The form of the wheel proving an inadequate remedy for the evils of shrinkagtg the annealing of the wholewheel has been re-- sorted to as a means of equalizing the tension of all its parts; but as heretofore practised the evil consequences of unequal shrinkage have been indicted upon the castin g to a-greater or lesser extent before being submitted to the annealing process. By my improvements and mode of treatment, however, this 'evil is effectually prevented by causing the wheel to cool slowly and equallyin allits parts from themement the casting is set in the mold till it may be handled with impunity, and the great heat of the casting in the first .instance being long continued, the'i'ron isthereby annealed and rendered very tough. Thus the common singleplate railroad-wheel, although it is one of the weakest products of the foundry if allowed to vcool in the ordinary way, is made by my mode of treatment to possess the greatest possible strength that is due to the substance of the metal, while at the same time the cost'of its manufacture is not increased.

The nature and object of my invention are accordingly to combine such improvements To obviate 2 sacos with the common cooling-pit as will in the first place facilitate the handlingaud placing of the wheels in proper position within the-pitat the greatest possible heat at which they can be moved after beingcast; and, secondly, tocause the wheels to cool slowly and equally in all their parts and in all parts of the pit.

To enable others skilled in the'art to make and use my invention, I will proceed to describe the saine, and also the process or treatment by which the casting is made to shrink equally in all its parts.

I construct a cylindrical chamber or pit, below the level of the molding-floor AA, of masonry or of plate or cast iron, as shown at B B, allowing the top edge to project about oneA inch above the door, for a purpose which will be presently explained. This chamber is some three or four inches larger in the clear than the diameter of the ilange ot' the proposed wheels,and within it, at equal distances apart. I attach to it three vertical guide-strips, C C C, which have respectively sutiicicnt projection to keep the`wheels in the center ot` the pit as they are depositedwithin it. The pit should also have sufficient depth or capacity to hold about ten wheels, placed tlatwise over each other at a little distance apart, as shown at D D D, for which purpose the spacersE E E are placed between them. These spacers are castiron rings having notches in the edge to clear the arms ot' the wheel, so that the bearing shallbe upon the plates of the wheels only,

, and they should be of such diameter as would about equally divide the weight of the wheel, so that the portion of the wheel within the spacer ma y serve asa counterbalanccto the exterior portion, the object being to insure such position to each wheel within the pit that it shall not be submitted to any strain that could alter its shape, as these castings are liable to warp if not properly bedded, owing to the great heat at which they are put into the pit. On the pit being filled with the newly-cast'wheels itis immediately closed by placing upon it the iron top plate or cope, F F, for the convenience of handlingwhich it is furnished with a staple or eye, G. Dry sand is spread over the plate lto a. depth of three or four inches, and to prevent the spreading of this sand over the floor 1 place upon thc tloor, around the top plate,F F, the portable ring E H, which I call the cope-ring, and which should be about tive inches greater diameter than the top plate. The covering sand being thus retained, as shown at K K, the pit is thereby hermetically sealed at top,'for if the sand were not secured in this manner the heated airand gases would blow out at the top joint, and thus seriously impair the action ofthe pit, as theheat would soon be dissipated if allowed to escape at the top of the pit. Y

'Io relieve the pressure within the pit, and at the same. time retain as much ofthe heat as possible, I attach to the lower part of thc pit the ventftube L, which rises above the floor AA, or may be conveyed to any convenient place.

This tube is furnished with a stop-cock, M, so as to close the vent when the pressure is rclieved. Sometimes I make these pits witha sub-chalnbcr or air-space, N, below the bottom plate, P, ot the pit, and communicating with the pit by means of one or more small holes passing through the said bottom plate.-

By this construction and arrangement the heat and gases evolved from the mass of incandescent metal within the pit are made to pass downward into the sub-chamber N, and from thence outward by the vent-tube L, which may beclosed bythe stop-cock when the heated air and gases cease to escape with force, thereby causing the heat to be the same in all parts of the pit, and consequently all the wheels within the pit will be equally annealed and tempered in all their parts, as I have experimentally ascertained; and I have also'experimentally ascertained that in those pits which are not vented from the bottoml the wheels in the bottom ot'such pits are not as well annealed and tempered as those at the top, and that such bottom wheels have not more than halt' the strength of the top wheels of such pits. The wheel-molds being poured with iron at a proper degree of heat, the wheels can be lifted from the sand` and placed within the pit in about tive minutes after being cast. I usually `cast ten wheels from a vessel holding sutiicient mttal t'or this purpose, litt them from the molds, place them in -the pit, and cover them with the top plate and sand in eight minutes, taking up the wheels in thesame order in which they are cast. The pitand contents should then remain undisturbed for about four days,in which time the wheels will besuiciently cooled to be removed with safety. 1

It is ofthe utmost importance that the wheels should be got into the pit and covered up before shrinkage commences, for, the wheels bei ing closed up at that high heat within a chamber from which radiation or escape of the heat 4 is very'slow, all the parts ofsuch wheels immediatel y acquire the same degree ot' heat, and as the heat diminishes it passes from every portion of them alike, thus causing all the parts of such wheels to shrink uniformly while cooling without being inuenced in any way by the thickness or thinness of such parts, thereby retaining the particles of the metal in their normal position in the castiug,and consequently in the full exercise oftheir cohesive attraction or tensile strength, and not only have such wheels the greatest possible strength, due

to the metal of whicl: they are composed, but v the longcontinned action of the high heat at which vthey arc placed in the pit has-the efect of greatly toughening the metal, thus per" mitting the use ot' a large quantity of wheelscrap in the mixture, and'thereby reducing thc cost of production, especially in those localities where such scrap is not required for other purposes; wheels thus treated con-- taining sixty or seventy per cent. of such scrap being found equal to those made trom mixtures of the best pig metal; and althlugh such wheels, if cooled in the mold, are liable to iiy'apart, (and have actually done so `from the derang'ement of the particlesof the metal byunequal shrinkage,) yet the same 'form of wheel and mixture of metal, whencooled in my improved pit, hasrequired three hundred f and fifteen blows of twenty-.two pound sled ges, plied with full swing by two vmen ot' over averagestrength, to merelypunch a hole through the central plate between the arms without cracking either the arms or rim,.showing that such wheels can be used 'with perfect safety 'under all conditions and for all 4purposes of railroad travel or transportation. v 1 do not claim the cooling of wheelsn pits or chambers, as that has lung been'practiced; but such pits or ehamoerswerefnot arranged or fitted. like mine, being either open at top 'or connecting bymeansof aline with a chimney, and being-destitute of the means by which the wheels may be accurately and expeditiously arrangedwithin such pits. The thin parts of the wheels were injuriously. cooled before-that could be accomplished; andsuch pits being vented at the top, any benefit that might be derived from their use was con'iined 'to the top wheels only.' 'Such pits or chamberscould not produce the same effects upon the castings `which are obtained by my improvements, these being so arranged as to permit the greatest possible expedition in securing the newlyfcast wheels within the pit; and whereas in the common pits the'whe'els are usally piled in vupon each, other without system or order, in ny pits they are placed in such .a manner that they cannot be subjected to anystrain or change of form, either from their individual weight or from the aggregated weight of those that may be placed uponthcm, Iwhich is particularly important, for to secure the full benetit of the pit the wheels must be placed Awithin it in an almost semi-plastic condition, the heat being such that theywould yield bytheir ownweight they may he placed, which is eectually prevente'd by theirf bein g truly placed and bedded 'upon each other by means of the guide-strips and spacers; and being hermetically inclosed atgthe high heat described with a.l covering that prevents the escape of the heat in an nplward direction it is retained within the pit till `the iron of thc wheelsis thoroughly tempered, and as thecoolingr of the inclo'sedv castings proceeds slowly and uniformly in all their parts, 'unequal shrinkage is eiectually prevented and the greatest possible strength due to the quality of the metal, secured to the casting.

tion, and operation of my improvements in pits or chambers for cooling or .annealing wheelcastings, what I claim therein as my own invention, and desire to secure-by Letters Pat'- ent, is-

' 1. The cooling or annealing pit herein de-` aranged for the purpose set forth.

the top plate, substantially as described.

3. The cooling or annealing pit, in combination with the guidestrips,or their equivalents,

scribed. y

WM. J. COCHRAN. Witnesses:

J oHN Commun, JOHN MCINTYRE.

to any unevenness in the bearing upon which `Havin g thus described the nature, construc-Y -scribed with a top covering and bottom vent,

.2. The arrangement of the cope-ring withl Aarranged and. operating substantially as del 

